Recently, with the spread of wireless communication devices, signals of various frequency bands have been propagated in the air. Thus, when a desired signal (hereinafter, referred to as a “desired signal”) is received, a reception device receives an interference signal in the same frequency band as that of the desired signal, along with the desired signal. This causes a problem in that the reception accuracy of the desired signal is degraded in the reception device by the interference signal received by the reception device along with the desired signal.
To solve this problem, a technique has been proposed which generates a replica of an interference signal (hereinafter, referred to as an “interference signal replica”) based on a spectrum of a received signal (hereinafter, referred to as a “reception signal”) and included in the received signal, and estimates a desired signal that is not affected by the interference signal by subtracting the interference signal replica from the reception signal (for example, see Non-Patent Document 1).
FIG. 11 is a block diagram showing a functional configuration of a reception device P1 configured using the related art. The reception device P1 includes an auxiliary antenna P101, an interference signal extraction section P102, a demodulation section P103, a deinterleaver P104, a FEC decoding section P105, an FEC encoding section P106, an interleaver P107, a modulation section P108, a phase amplitude adjustment section P109, an antenna P110, a delay section P111, a combining section P112, a demodulation section P113, a deinterleaver P114, and an FEC decoding section P115.
An antenna having directivity is applied to the auxiliary antenna P101, and the auxiliary antenna P101 receives a signal arriving from a direction of a transmission source of an interference signal whose position is identified. The interference signal extraction section P102 extracts the interference signal from the signal received by the auxiliary antenna P101 based on content of a communication scheme identified from the interference signal. The demodulation section P103 demodulates the interference signal extracted by the interference signal extraction section P102. The deinterleaver P104 deinterleaves a demodulation signal generated by the demodulation section P103. The FEC decoding section P105 decodes the demodulation signal deinterleaved by the deinterleaver P104 according to Forward Error Correction (hereinafter, referred to as FEC), and generates a bit sequence in which an error bit or error bits are corrected. The FEC encoding section P106 codes the bit sequence generated by the FEC decoding section P105 according to FEC, and generates a coded signal. The interleaver P107 interleaves the coded signal generated by the FEC encoding section P106. The modulation section P108 generates an interference signal replica by modulating the coded signal interleaved by the interleaver P107. The amplitude and phase control section P109 changes a phase of the interference signal replica generated by the modulation section P108 by 180 degrees. The amplitude and phase control section P109 generates a reversed-phase interference signal replica by causing an amplitude of the phase-changed interference signal replica to be consistent with an amplitude of the interference signal extracted by the interference signal extraction section P102. The combining section P112 generates the reception signal in which an interference signal component is reduced by combining the reception signal received by the antenna P110 and delayed by the delay section P111 with the reversed-phase interference signal replica generated by the amplitude and phase control section P109. The demodulation section P113 demodulates the reception signal in which the interference signal component is reduced. The deinterleaver P114 deinterleaves the demodulation signal generated by the demodulation section P113. The FEC decoding section P115 decodes the demodulation signal deinterleaved by the deinterleaver P114 according to FEC, generates a bit sequence in which an error bit or error bits are corrected, and outputs reception data.
The reception device P1 configured as described above generates the interference signal replica by the auxiliary antenna P101, the interference signal extraction section P102, the demodulation section P103, the deinterleaver P104, the FEC decoding section P105, the FEC encoding section P106, the interleaver P107, and the modulation section P108, subtracts the interference signal replica from the reception signal received by the antenna P110 using the amplitude and phase control section P109 and the combining section P112, and generates a desired signal.    [Non-patent Document 1] TOSHIYUKI KAITSUKA, TAKEO INOUE, “Interference Cancellation System for Satellite Communication Earth Station”, IEEE Transactions on Communications, Vol. com-32, No. 7, pp. 796-803, July 1984.